However, drinking water is not the most stringent guideline for water uses. Humans are actually fairly tolerant of junk in drinking water compared to other forms of life. Amphibians for example are much more sensitive to contaminants in water than humans. As home to amphibians and other sensitive organisms, discharge to wetlands can require better quality water than standard drinking water quality.

Not to mention, water that is perfectly fine chemically and biologically can still kill fish and amphibians if it is too warm. Many aquatic animals have very narrow thermal tolerances.